Abstract:
Brachypodium sylvaticum, an invasive grass in Oregon, has the potential to cause ecosystem collapse by altering forest fire regimes. To examine interactions with fire we divided two sites in the Willamette National Forest into eight units and randomly selected half for treatment with prescribed fire in spring 2011. B. sylvaticum did not affect prescribed fire intensity or severity. However, fire severity negatively affected B. sylvaticum abundance (F4,43 = 5.01, P = 0.002). In the field, prescribed fire decreased germination (F1,96 = 7.54, P = 0.007, R2 = 0.46) in comparison with the control (0.14 ± 0.07/plot burned versus 0.30 ± 0.16/plot controls). Similar to abundance and germination, fire severity was the driver significantly affecting dispersal (F4,27 = 5.50, P = 0.002). These results indicate that hot fires have the potential to control the grass, but low severity fires will likely make it worse.
This thesis includes previously unpublished coauthored material.
